Woods, 32, endorsed GM products including Buick for the past 9 years. He had been under contract through 2009, Pete Ternes, a spokesman for the Detroit-based automaker, said today.

The need for "budget efficiencies during a difficult economy" contributed to the decision, according to a statement from GM, which is seeking to cut U.S. marketing expenses by 20 percent. Sales of Buick vehicles dropped 24 percent through the first 10 months of this year, outpacing the 20 percent decline for all of GM's cars and light trucks.

As part of a drive to cut $15 billion in costs, GM is no longer keeping the 562 clocks in working order, which will eliminate the expense of replacing and disposing of the clock's batteries and the cost of resetting them twice a year for daylight-saving time.

It's not the only new measure GM is taking to save every last nickel. In its Renaissance Center headquarters, employees working late have to climb stairs when navigating its labyrinth of lower floors -- the company now stops the escalators at 7 p.m. In designated cleanup areas of certain offices, the company has changed the type of wipe-up towels it buys. In a memo to employees, a staffer explained this will lower GM's "cost per wipe."